Oars, 265, b.
Oath (Greek), 218, a.
(Roman), 218, b.
October-horse, 280, a.
Officers, duty of, 75, b.
parade of, 75, b.
Olympiad, 276, a.
Olympic games, 274, a.
Oracles, 276, b.
Orders of architecture, 101, b; 102, a.
Organ, 210, a.
Ostracism, 172, a.
Oven, 182, a.
Ounce, 105, a.